Our research program is broadly aimed at understanding the biochemistry and physiology of iron in an effort to improve iron nutrition in the human population, and we are working toward the following goals: 1. Synthesis and nutritional evaluation of efficacious iron supplements for specific therapeutic and prophylactic applications: New forms of chelated and polymeric ferric iron offer distinct advantages over ferrous sulfate and conventional food iron additives for oral therapy and fortification of foodstuffs. 2. Establishing the mechanisms of gastrointestinal iron absorption and its regulation: We are developing an hypothesis that the ability of the intestine to absorb and transport iron is determined not by body iron stores but by the amount of nutritionally available iron to which the intestinal mucosa has become conditioned. 3. Understanding the mechanisms of iron storage: We are examining the properties of the iron storage protein, ferritin, in vivo and in vitro to increase our knowledge of the metabolism of excess iron. We are examining the biochemical role of copper in facilitating the mobilization of iron from ferritin storage. 4. Development of potential tests of iron assimilation in man: We are developing animal models for measuring the absorption and excretion of inorganic cobalt to measure relative biological availability of iron. This test shows promise as a non-radioactive technique for "probing" iron absorption in the human. We are investigating the origin and significance of serum ferritin in the rat to develop a rational basis for the use of serum ferritin immunoradiometric assay as a valid indicator of iron stores in the human.